Substrate processing using a member comprising an oxide of a group IIIB metal

ABSTRACT

An erosion resistant member that may be used in the processing of a substrate in a plasma of a processing gas, comprises at least a portion that may be exposed to the plasma of the processing gas and that contains more than about 3% by weight of an oxide of a Group IIIB metal. The portion may also further contain a ceramic compound selected from silicon carbide, silicon nitride, boron carbide, boron nitride, aluminum nitride, aluminum oxide, and mixtures thereof.

CROSS-REFERENCE

This is a divisional application of patent application Ser. No.09/589,871, filed Jun. 2, 2000 U.S. Pat. No. 6,352,611 which is acontinuation of patent application Ser. No. 09/124,323 filed on Jul. 29,1998 U.S. Pat. No. 6,123,791.

BACKGROUND

The present invention relates to an apparatus having an erosionresistant member useful in the processing of substrates.

The semiconductor industry relies on high throughput, single substrateprocessing reactors which can be used for a variety of differentprocesses such as thermal chemical vapor depositions (CVD),plasma-enhanced CVD (PECVD), plasma-assisted etching, and depositiontopography modification by sputtering. Some processing reactors includeprocessing reactor chambers having a dielectric member (i.e., adielectric window) wherethrough processing power passes to aid insustaining a plasma from a processing gas within the reactor chamber forprocessing a wafer substrate.

Process kits are sometimes employed within the reactor chamber as an aidto processing a wafer substrate. Process kits typically include acapture ring which is supported by a pedestal assembly for retaining awafer substrate in a generally stationary position for processing.Process kits also typically include a focus ring which in operation issupported by the capture ring for assisting in confining plasmaprocessing gas over the wafer substrate to optimize the processing ofthe same.

Dielectric members (e.g., dielectric windows) and process kits aregenerally constructed of a ceramic material, such as high parity aluminaceramics containing 99.5% by weight or higher aluminum oxide (Al₂O₃).When high density halogen-containing plasmas contact alumina dielectricmembers and alumina process kits during etching of wafer substrates,erosion of alumina occurs, causing the formation of large particles andcontaminant compounds which can damage patterned wafer substrates.

Therefore, what is needed and what has been invented is an improvedceramic composition of matter from which dielectric members and processkits may be constructed. What is further needed and what has beenfurther invented are dielectric members (i.e. dielectric windows) andprocess kits which are all highly resistant to erosion during etching ofa wafer substrate in a high density plasma of an etchant gas.

SUMMARY

An erosion resistant member that may be used in the processing of asubstrate in a plasma of a processing gas, the member comprising atleast a portion that may be exposed to the plasma of the processing gas,said portion comprising more than about 3% by weight of an oxide of aGroup IIIB metal.

An erosion resistance member that may be used in the processing of asubstrate in a plasma of an etchant gas, the member comprising at leasta portion that may be exposed to the plasma of the etchant gas, saidportion comprising yttrium oxide and aluminum oxide.

A plasma reactor for processing a substrate, the plasma reactorcomprising:

a pedestal to support a substrate;

a gas inlet to introduce a processing gas into the reactor;

a power supply to provide energy that may be coupled to the processinggas to form a plasma from the processing gas;

a member having at least a portion that may be exposed to the plasma ofthe processing gas, said portion comprising more than about 3% by weightof an oxide of a Group IIIB metal; and

a pump adapted to pump out the processing gas from the reactor.

An etching reactor for etching a substrate, the reactor comprising:

a pedestal to support a substrate;

a gas inlet to introduce an etchant gas into the reactor, the etchantgas comprising a halide gas;

a power supply to provide energy that may be coupled to the etchant gasto form a plasma from the processing gas;

a member having at least a portion that may be exposed to the plasma ofthe etchant gas, said portion comprising yttrium oxide and aluminumoxide;

a pump adapted to pump out the processing gas from the reactor.

A substrate processing method comprising

(a) placing a substrate in a process chamber;

(b) introducing a processing gas into the process chamber;

(c) forming a plasma from the processing gas;

(d) exposing at least a portion of an erosion resistant member to theplasma, the member comprising more than about 3% by weight of an oxideof a Group IIIB metal; and

(e) exhausting the processing gas from the process chamber.

A method of fabricating a plasma erosion resistant member comprising:

(a) preparing a mixture comprising more than about 3% by weight of anoxide of a Group IIIB metal;

(b) forming the mixture into the shape of the member; and

(c) sintering the mixture.

DRAWINGS

FIG. 1 is a partial side elevational view of a process chamber having apedestal assembly disposed therein including a wafer-capture ringcomprising the ceramic composition of the present invention and engagedto the pedestal assembly for retaining a wafer substrate thereon, and afocus ring comprising the ceramic composition of the present inventionand capable of being supported by the pedestal assembly for assisting inconcentrating a plasma of a processing gas over a wafer substrate;

FIG. 2 is a top plan view of the focus ring comprising the ceramiccomposition of the present invention;

FIG. 3 is a bottom plan view of the focus ring in FIG. 2;

FIG. 4 is a vertical sectional view taken in direction of the arrows andalong the plane of line 4—4 in FIG. 2;

FIG. 5 is a top plan view of the wafer-capture ring comprising theceramic composition of the present invention;

FIG. 6 is a bottom plan view of the wafer-capture ring in FIG. 5;

FIG. 7 is a vertical sectional view taken in direction of the arrows andalong the plane of line 7—7 in FIG. 5; and

FIG. 8 is a simplified cut-away view of an inductively coupled RF plasmareactor having a dome-shaped dielectric ceiling comprising the ceramiccomposition of the present invention.

DESCRIPTION

Referring in detail now to the drawings wherein similar parts of thepresent invention are identified by like reference numerals, there isseen a process chamber, schematically illustrate as 10, having a chamberwall 11 and a pedestal assembly, generally illustrated at 12, forsupporting a substrate, such as substrate or semiconductor wafer 13,while being processed within the process chamber 10. The chamber wall 11supports a dielectric member 20. A process kit is seen in FIG. 1 asbeing generally illustrated as 14 and supported by the pedestal assembly12 for assisting in the processing of the wafer substrate 13. Theprocess kit 14 consists of a wafer-capture ring 16 connected to thepedestal assembly 12 for keeping the wafer substrate 13 stationary whileit is being processed. The process kit 14 also consists of a focus ring18 for assisting in keeping a high density plasma 94 of a processing gasconcentrated and/or positioned over the wafer substrate 13. Thewafer-capture ring 16 and the focus ring 18 have respective ringopenings 16 a and 18 a (see FIGS. 2-7).

The wafer substrate 13 may be processed within the process chamber 10 byany plasma processing procedure, such as by plasma etching forpatterning integrated circuit (IC) metal interconnect devices. Otherforms of processing substrates which are included within the spirit andscope of the present invention include chemical vapor deposition,physical vapor deposition, etc. During the plasma process, processingpower (e.g., RF power, magnetron power, microwave power, etc.) passesthrough the dielectric member 20, which includes a dielectric window ofa nonconductive material such as a ceramic dome, etc., and becomescoupled to the high density plasma 94 of the processing gas. If theplasma process is plasma etching, metal etching of metals (e.g.platinum, copper, aluminum, titanium, ruthenium, iridium, etc.) isconducted while being supported by substrates.

The dielectric member 20 and the process kit 14 are manufactured of aceramic material. When the wafer substrate 13 is processed, ceramicdielectric member 20 and ceramic process kit 14 erodes, causinggeneration of contaminating particulates. Erosion of the dielectricmember 20 and the process kit 14 is particularly profound when the wafersubstrate 13 is processed by etching in a high density plasma of anetchant gas, especially when the etchant gas is a halogen-containingetchant gas, such as Cl₂ and BCl₃. High density plasma may be defined asa plasma of an etchant gas having an ion density greater than about10⁹/cm³, preferably greater than about 10¹¹/cm³. The source of the highdensity plasma may be any suitable high density source, such as electroncyclotron resonance (ECR), helicon resonance or inductively coupledplasma (ICP)-type sources.

It has been discovered that if the dielectric member 20 and the processkit 14 are manufacture from the ceramic composition of the presentinvention, the dielectric member 20 and the process kit 14 essentiallydo not erode during processing of the wafer substrate 13, especially byplasma etching in a high density plasma. Therefore, the dielectricmember 20 (i.e. the dielectric window), as well as the process kit 14including the wafer-capture ring 16 and the focus ring 18, comprise theceramic composition of the present invention, which includes a ceramiccompound and an oxide of a Group IIIB metal from the periodic table byMendeleef and as shown on page 789 of The Condensed Chemical Dictionary,tenth edition as revised by Gessner G. Hawley, and published by VanNostrand Reinhold Company.

The ceramic compound for the ceramic composition is a compound that istypically electrically insulating and the crystallinity of which variesamong amorphous, glassy, microcrystalline, and singly crystalline,dependent on material and its processing. The ceramic compound ispreferably an essentially non-porous material. It is a good electricalinsulator, and because it can be made in a relatively pure form(approximately 99% by weight or better) it has a low degree of chemicalreactivity in the plasma environment. The ceramic compound may be ansuitable ceramic compound that may combine with the oxide of Group IIIBmetal to form a highly erosion-resistive ceramic structure, especiallywhen processing power is passing through the dielectric member 20 duringetching of a substrate (e.g. wafer substrate 13) in a high densityplasma (e.g. high density plasma 94) of a processing gas. The ceramiccompound is preferably selected from the group consisting of siliconcarbide (SiC), silicon nitride (Si₃N₄), boron carbide (B₄C), boronnitride (BN), aluminum nitride (AlN), aluminum oxide (Al₂O₃) andmixtures thereof. More preferably, the ceramic compound comprisesaluminum oxide (Al₂O₃), especially since aluminum oxide is relativelyinexpensive and readily available.

The aluminum oxide should be sufficiently pure that it does not“out-gas” or include contaminants that could be sputtered onto thesubstrate during process operation, and it should be chemically stablewhen exposed to the particular etching processes contemplated. Whilealuminum oxide is a preferred ceramic compound for a preferredembodiment of the present invention, it is to be understood that thespirit and scope of the present invention includes other insulativematerials which can provide similar effects, for example, the oxides andfluorides of aluminum, magnesium, and tantalum. Some of these arecrystalline or polycrystalline insulating materials. Some may be made asglassy ceramics. Thus, the aluminum oxide or other metal oxide ceramicscan be a single crystal oxide, polycrystalline oxide, or amorphousoxide. These materials are all electrically insulating and generallyrobust in a plasma etching environment and should not create undesiredparticulates in presence of the high density plasma 94. Other materialscan alternatively be used.

Group IIIB metal is a metal preferably selected from the groupconsisting of scandium (Sc), yttrium (Y), the cerium subgroup, theyttrium subgroup, and mixtures thereof. The cerium subgroup includeslanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd),promethium (Pm), and samarium (Sm). The yttrium subgroup includeseuropium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium(Ho), erbium (Er), thulium (Tm), ytterbium (Yb) and lutetium (Lu). In apreferred embodiment of the present invention, the Group IIIB metal isyttrium (Y); thus, the preferred oxide of a Group IIIB metal is Y₂O₃.

The dielectric member 20 and process kit 14 may be manufactured by anysuitable ceramic manufacturing process, such as those processesdescribed in Volume 5, entitled “Ceramics and Glasses,” of theEngineered Materials Handbook by ASM International © 1991, andincorporated herein by reference thereto. Preferably, the dielectricmember 20, the wafer-capture ring 16, and the focus ring 18 aremanufactured by the following steps: (i) admixing the ceramic compoundin powdered form, and the oxide of a Group IIIB metal in powdered formwith a suitable additive agent, and a suitable binder agent to produce apowdered raw mixture; (ii) forming the powdered raw mixture to produce aformed powdered raw mixture; (iii) thermal processing (i.e., sintering)the formed powdered raw mixture to produce a rough ceramic product (i.e.a rough dielectric member 20 or a rough process kit 14); and (iv)finishing the rough ceramic product to produce a finished ceramicproduct (i.e. a finished dielectric member 20 or a finished process kit14).

The powdered raw mixture which is to be subsequently formed comprisesany suitable proportions of the ceramic compound, the oxide of GroupIIIB metal, the suitable additive agent and the suitable binder agent.Preferably, the powdered raw mixture comprises from about 10% by weightto about 85% by weight of the ceramic compound, from about 3% by weightto about 60% by weight of the oxide of a Group IIIB metal, from about0.1% by weight to about 6% by weight of the suitable additive agent, andfrom about 5% by weight to about 35% by weight of the suitable binderagent. More preferably, the powdered raw mixture comprises from about20% by weight to about 75% by weight of the ceramic compound, from about5% by weight to about 55% by weight of the oxide of a Group IIIB metal,from about 0.5% by weight to about 5% by weight of the additive agent,and from about 10% by weight to about 30% by weight of the binder agent.Most preferably, the powdered raw mixture comprises from about 25% byweight to about 70% by weight of the ceramic compound, from about 10% byweight to about 50% by weight of the oxide of a Group IIIB metal, fromabout 0.5% by weight to about 4.5% by weight of the additive agent, andfrom about 12% by weight to about 28% by weight of the binder agent.

The suitable additive agent may be any suitable additive that leaves noresidue, or ash, or other chemical contamination that will interferewith the thermal or sintering process or adversely affect the ultimatedesired properties of the dielectric member 20 and the process kit 14.The additive agent is typically transient, but a portion of the additiveagent is usually a permanent part of the chemical make-up of theultimate ceramic product. The suitable additive agent may be any of theadditive agents or suitable mixtures thereof disclosed in the previouslymentioned Engineering Materials Handbook, such as by way of example onlyany suitable additive agent selected from the group consisting ofsolvents, dispersants, sintering aids, dopants, preservatives,surfactants, and mixtures thereof. Solvents include water, organic polarsolvents (e.g., fatty acids, amines, alcohols, aldehydes, esters,ethers, ketones, etc.), and organic nonpolar solvents (e.g. benzene,toluene, etc.). Dispersants comprise organic macromolecules anddeflocculants (e.g. nonorganic polyelectrolytes) and insure thatpowdered raw materials do not recombine or flocculate. Sintering aidsare typically combinations of one or more oxides that may be addedprimarily to control grain growth and enhance densification. Graingrowth and densification may also be affected by dopants which are oxidechemical additives, more typically oxides of metals have valencesdifferent from the primary oxide (e.g. the ceramic compound), thatinteract with surface chemistry for subsequently altering surfaceenergetics. Preservatives may be added to insure that microbial actiondoes not degrade binder properties during any holding periods.Surfactants modify interfacial characteristics between a dispersed phaseand a solvent; and function as wetting agents for enabling effectivetotal wetting the powdered solids by the solvent, as antifoaming agentsfor minimizing bubble-type pores, and as rheological altering agents foraltering the rhealogical properties of the solvent-powdered raw materialcomposition and acting as plasticizers and/or lubricants.

The suitable binder agent may be any suitable binder which is capable ofimparting sufficient strength and appropriate elastic properties to theformed powdered raw mixture for facilitating the handling and shaping ofthe formed powdered raw mixture during thermal processing of the same.The binder agent is typically transit, but a portion of the binder agentis usually a permanent part of the ultimate ceramic product. Thesuitable binder agent may be any of the binders, or suitable mixturesthereof, disclosed in the previously mentioned Engineering MaterialsHandbook, such as by way of example only any suitable binder agentselected from binders for aqueous systems, such as colloidal typebinders (e.g. cellulose, clays), carbohydrate-derived organic binders(e.g. methyl cellulose, sodium alginate, natural gums, etc.),non-carbohydrate-derived organics (e.g. polyvinyl alchohol, acrylicresins, etc.), and binders for nonaqueous (organic solvent) systems,such as polyvinyl butyral and polymethylmethacrylate, and suitablemixture(s) of any of the foregoing binder agents.

After the powdered raw mixture has been produced it is then subsequentlyformed into a formed powdered raw mixture. Forming may be accomplishedby any suitable process (e.g. casting, extrusion, dry pressing, etc.)that consist of compaction of the powdered raw mixture into a porousshape to achieve the greatest degree of particle packing and high degreeof homogeneity. In a preferred embodiment of the invention, the formedpowdered raw mixture is produced by dry pressing which is sometimesreferred to as dust pressing, die-pressing or uniaxial compaction. Drypressing of the powdered raw mixture includes consolidating the powderedraw mixture inside a die cavity into a predetermined shape though theuse of applied pressure acting in a uniaxial direction. In the presentinvention, the predetermined shape is preferably the shape of thedielectric member 20 (i.e. the dielectric window) or the shape of thewafer-capture ring 16 and the focus ring 18. Dry pressing is well knownto those possessing ordinary skill in the art and is thoroughlydescribed in the previously mentioned Engineered Materials Handbook,which has been incorporated herein by reference thereto. Dry pressingbroadly comprises filling the die cavity with the powdered raw mixture,pressing or compacting the powdered raw mixture within the die cavity toproduce a compacted or formed powdered raw mixture, and subsequentlyejecting the formed powdered raw mixture.

The formed powdered raw mixture may be thermally processed in anysuitable manner, preferably by sintering which provides interparticlebonding that generates the attractive forces needed to hold together theotherwise loose formed powdered raw mixture. Sintering is the result ofatomic motion stimulated by a high temperature and causes the particlesof the formed powdered raw mixture to bond together when heated to ahigh temperature. Sintering of the formed powdered raw mixture of thepresent invention may be performed with any suitable furnace (e.g.combustion or electric) at any suitable temperature, pressure, heatingand cooling rate, and furnace atmospheric composition. Suitabletemperatures, pressures, heating and cooling rates, and suitableatmospheric composition are well known to those possessing ordinaryskill in the art. The formed powdered raw mixture may be sintered in anelectrically heated furnace having an oxide ceramic heating element,such as lanthanum chromit (LaCr₂O₄) or stabilized zirconia, and air asthe furnace atmospheric composition.

After formed powdered raw mixture has been thermally processed, a roughceramic product (i.e. a rough dielectric member 20 or a rough processkit 14) is produced. The rough ceramic product is preferablysubsequently finally shaped, such as by grinding, lapping or polishing.If the rough ceramic product is a rough dielectric member 20 in theshape of a dielectric dome, it is preferably finally shaped by grinding.If the rough ceramic product is a rough wafer-capture ring 16 or a roughfocus ring 18, it is preferably finally shaped by lapping or polishing.Grinding employs an abrasive machining method where diamond abrasivesare held fixed in a grinding wheel and applied against the work surface(e.g. the inside and outside surface of a dome-shaped dielectric member20) in a variety of configurations. Lapping is free-abrasive machiningmethod where loose or bonded abrasives in a low-pressure, low-speedoperation achieve high geometric accuracy, correct minor shape errors,improve surface finish, or provide tight fits between mating surfaces.Polishing is also a free-abrasive machining method where loose abrasivesof fine particle size and preseleted hardness are employed to improvesurface finish. Grinding, lapping, and polishing methods for shaping arough ceramic product are all well known to those artisans possessingordinary skill in the art and are thoroughly described in the previouslymentioned Engineered Materials Handbook.

The ceramic composition for the finished dielectric member 20 andprocess kit 14 comprises from about 30% by weight to about 95% by weightof the ceramic compound, from about 5% by weight to about 70% by weightof the oxide of a Group IIIB metal, and less than about 15% by weight(e.g. from about 0.5% by weight to about 15% by weight) of thecombination of the suitable additive agent and the suitable binder agentsince these agents are typically transient during the thermalprocessing. More preferably, the ceramic composition for the finisheddielectric member 20 and process kit 14 comprises from about 40% byweight to about 85% by weight of the ceramic compound, from about 15% byweight to about 60% by weight of the oxide of a Group IIIB metal, andless than about 10% by weight (e.g. from about 0.5% by weight to about15% by weight) of the additive agent and the binder agent; and mostpreferably from about 50% by weight to about 75% by weight of theceramic compound, from about 30% by weight to about 45% by weight of anoxide of a Group IIIB metal, and less than about 5% by weight (e.g. fromabout 0.5% by weight to about 5% by weight) of the combination of theadditive agent and the binder agent. Thus, the ceramic compositioncomprises a major proportion of the ceramic compound and a minorproportion of the oxide of a Group IIIB metal. When the ceramic compoundis Al₂O₃ and the oxide of a Group IIIB metal is Y₂O₃, a preferredceramic composition comprises from about 60% by weight to about 65% byweight Al₂O₃, from about 35% by weight to about 40% by weight Y₂O₃, andless than about 2.5% by weight (e.g. from about 0.5% by weight to about2.5% by weight) and the combined additive and binder agents.

The ceramic composition of the present invention may be employed tomanufacture any potentially erosive part of any processing apparatus,such as an electron cyclotron resonance (ECR) source reactor, a heliconsource reactor, a helical resonator reactor, or an inductively coupledplasma reactor. Preferably, the ceramic composition of the presentinvention is employed to manufacture a dielectric window (i.e. adome-shaped dielectric member 20 identified as “62” below) of aninductively coupled plasma reactor producing an inductive plasma sourceby inductively coupling a plasma in an associated decoupled plasmasource etch chamber, which decouples or separates the ion flux to thewafer substrate 13 and the ion acceleration energy.

Inductively coupled plasma reactors are currently used to performvarious processes on semiconductor wafers (e.g. wafer substrate 13)including metal etching, dielectric etching, chemical vapor deposition,and physical vapor deposition, as some examples. In an etch process, onadvantage of an inductively coupled plasma is that a high density plasmaion density is provided to permit a large etch rate with a minimalplasma D.C. bias, thereby permitting more control of the plasma D.C.bias to reduce device damage. For this purpose, the source power appliedto the inductive coil and the D.C. bias power applied to the waferpedestal are separately controlled RF supplies. Separating the bias andsource power supplies facilitates independent control of ion density andion energy, in accordance with well-known techniques. Plasma in aninductive source is created by application of RF power to a non-resonantinductive coil or to a planar coil. The application of RF power to anon-resonant inductive coil results in the breakdown of the process gaswithin a dielectric discharge chamber by the induced RF electric fieldwhich passes through the dielectric discharge chamber. Therefore, thecoil inductor provides RF power which ignites and sustains the plasma ofthe processing gas.

A preferred inductively coupled plasma reactor, which includes adielectric window comprising the ceramic composition of the presentinvention, is that which inductively couples a plasma in a decoupledplasma source etc. chamber sold under the trademark DPS™ owned byApplied Materials, Inc., 3050 Bowers Avenue, Sant Clara, Calif.95054-3299. The DPS™ brand etch chambers decouples or separates the ionflux to the substrate wafer 13 from the ion acceleration energy and maybe any of the DPS brand etch chambers of the inductively coupled plasmareactors disclosed in U.S. Pat. No. 5,753,044, entitled “RF PLASMAREACTOR WITH HYBRID CONDUCTOR AND MULTI-RADIUS DOME CEILING” andassigned to the present assignee and fully incorporated herein byreference thereto as if repeated verbatim immediately hereinafter.Referring now to FIG. 8 for one preferred embodiment of an inductivelycoupled RF plasma reactor from U.S. Pat. No. 5,753,044 there is seen aninductively coupled RF plasma reactor generally illustrated as 90,having a reactor chamber, generally illustrated as 92, wherein the highdensity plasma 94 or neutral (n) particles, positive (+) particles, andnegative (−) particles are found. The reactor chamber 92 has a groundedconductive cylindrical sidewall 60 and a dielectric window 62 whichcomprises the ceramic composition of the present invention. Theinductively coupled RF plasma reactor 90 further comprises a waferpedestal 64 for supporting a (semiconductor) wafer 110 in the center ofthe reactor chamber 92, a cylindrical inductor coil 68 surrounding anupper portion of the reactor chamber 92, a cylindrical inductor coil 68surrounding an upper portion of the reactor chamber 92 beginning nearthe plane of the top of the wafer 110 or wafer pedestal 64 and extendingupwardly therefrom toward the top of the reactor chamber 92, an etchinggas source 72 and gas inlet 74 for furnishing an etching gas into theinterior of the chamber 92, and a pump 76 for controlling the pressurein the chamber 92. The coil inductor 68 is energized by a plasma sourcepower supply or RF generator 78 though a conventional active RF matchnetwork 80, the top winding of the coil inductor 68 being “hot” and thebottom winding being grounded. The wafer pedestal 64 includes aninterior conductive portion 82 connected to the bias RF power supply orgenerator 84 and an exterior grounded conductor 86 (insulated from theinterior conductive portion 82). Thus the plasma source power applied tothe coil inductor 68 by the RE generator 78 and the DC bias RE powerapplied to the wafer pedestal 64 by generator 84 are separatelycontrolled by RE supplies. Separating the bias and source power suppliesfacilitates independent control of ion density and ion energy, inaccordance with well-known techniques. To produce high density plasma 94as an inductively coupled plasma, the coil inductor 68 is adjacent tothe reactor chamber 92 and is connected to the RE source power supply orthe RE generator 78. The coil inductor 68 provides the RE power whichignites and sustains the high ion density of the high density plasma 94.The geometry of the coil inductor 68 can in large part determine spatialdistribution of the plasma ion density of the high density plasma 94within the reactor chamber.

Uniformity of the plasma density spatial distribution of the highdensity plasma 94 across the wafer 110 is improved (relative to conicalor hemispherical ceilings) by shaping the dielectric window 62 in amulti-radius dome and individually determining or adjusting each one ofthe multiple radii of the dielectric window 62. The multiple-radius domeshape of the dielectric window 62 somewhat flattens the curvature of thedielectric window 62 around the center portion of the dielectric window62, the peripheral portion of the dielectric window 62 having a steepercurvature.

While the present invention has been described herein with reference toparticular embodiments thereof, a latitude of modification, variouschanges and substitutions are intended in the foregoing disclosure, andit will be appreciated that in some instances some features of theinvention will be employed without a corresponding use of other featureswithout departing from the scope and spirit of the invention as setforth. Therefore, many modifications may be made to adapt a particularsituation or material to the teachings of the invention withoutdeparting from the essential scope and spirit of the present invention.It is intended that the invention not be limited to the particularembodiment disclosed as the best mode contemplated for carrying out thisinvention, but that the invention will include all embodiments andequivalents falling within the scope of the appended claims.

What is claimed is:
 1. An erosion resistant member that is used in theprocessing of a substrate in a plasma of a processing gas, the membercomprising at least a portion that is exposed to the plasma of theprocessing gas, said portion comprising more than about 3% by weight ofan oxide of a Group IIIB metal.
 2. A member according to claim 1 whereinthe portion of the member comprises more than about 5% by weight of theoxide of the Group IIIB metal.
 3. A member according to claim 1 whereinthe portion of the member comprises less than about 60% by weight of theoxide of the Group IIIB metal.
 4. A member according to claim 1 whereinthe oxide of the Group IIIB metal comprises yttrium oxide.
 5. A memberaccording to claim 1 wherein the oxide of the Group IIIB metal consistsessentially of yttrium oxide.
 6. A member according to claim 1 whereinthe portion of the member further comprises a ceramic compound selectedfrom silicon carbide, silicon nitride, boron carbide, boron nitride,aluminum nitride, aluminum oxide, and mixtures thereof.
 7. A memberaccording to claim 6 wherein the portion of the member comprises lessthan about 95% by weight of the ceramic compound.
 8. A member accordingto claim 6 wherein the ceramic compound comprises aluminum oxide.
 9. Amember according to claim 6 wherein the ceramic compound consistsessentially of aluminum oxide.
 10. A member according to claim 1 whereinthe member is a dielectric member.
 11. A member according to claim 1wherein the member is a process kit.
 12. A member according to claim 1wherein the portion of the member comprises more than about 10% byweight of the oxide of the Group IIIB metal.
 13. An erosion resistantmember that is used in the processing of a substrate in a plasma of anetchant gas, the member comprising at least a portion that is exposed tothe plasma of the etchant gas, said portion comprising (i) more thanabout 3% by weight of yttrium oxide and (ii) aluminum oxide.
 14. Amember according to claim 13 wherein the portion of the member comprisesless than about 60% by weight of the yttrium oxide.
 15. A memberaccording to claim 13 wherein the portion of the member comprises lessthan about 95% by weight of the aluminum oxide.
 16. A member accordingto claim 13 wherein the portion of the member consists essentially ofyttrium oxide and aluminum oxide.
 17. A member according to claim 13wherein the member is a dielectric member.
 18. A member according toclaim 13 wherein the member is a process kit.
 19. A member according toclaim 13 wherein the portion of the member comprises more than about 10%by weight the oxide of the Group IIIB metal.